This invention relates generally to washing machines and, more particularly, to a dam for use in tub sumps for preventing debris from flowing into the drain pump inlet prior to start-up of the pump motor.
Clothes washing machines typically include a clothes basket located within a tub. A water or tub outlet is located in a bottom portion of the tub, and a drain pump typically is located below the tub in flow communication with the outlet. In one known embodiment, the tub includes a helical flow path and a sump is located at the lower end of the path. The water outlet is an opening in the tub at the location of the sump and a conduit, sometimes referred to as a drain hose, extends from the outlet to the inlet of the pump.
In operation, water in the tub drains down along the helical flow path and into the sump. At selected times during a wash cycle, e.g., just prior to and during a spin cycle, the drain pump is energized and the pump draws water through the tub outlet and into the pump. Draining the free water, i.e., water not absorbed in clothes located in the basket, from the tub prior to and during the spin cycle improves washing machine performance by decreasing the occurrences and severity of out of balance loads.
With the above described washing machine configuration, debris flows with the water and into the sump. For example, if a rubber-backed rug is in the basket, some rubber particles will flow with the water down to the sump. During an agitation cycle, and even though the pump is not energized, some debris may flow through the tub outlet and into the drain hose. Some of the debris may even flow through the drain hose and to the inlet of the idle pump. The debris may collect in the hose and at the pump outlet, and such debris may plug the hose and pump. Therefore, when the pump is energized, the water may not be drained from the tub. In order to resume normal operations, the drain hose and pump inlet must be cleared, which typically requires some disassembly of the machine.
To prevent debris from flowing into the drain hose and into the pump inlet prior to activation of the pump, it is known to position traps or strainers over the tub outlet. Such traps and strainers collect debris and prevent debris from flowing through the tub outlet. Although known traps and strainers are effective at collecting debris, at least some known traps and strainers are complex to fabricate and assemble, which increases the cost of the washing machine. In addition, such traps and strainers may become plugged and inhibit the free flow of water from the tub through the outlet. Of course, limiting the free flow of water from the tub could lead to increasing the occurrence and severity of out of balance loads.
It would be desirable to prevent debris from plugging the drain hose and pump without substantially inhibiting the free flow of water through the tub outlet. It also would be desirable to provide such results using a simple structure which does not significantly increase the cost or complexity of the washing machine.
These and other objects may be attained by a washing machine including a tub having a helical flow path defined by a channel and a sump located at a lower end of the channel. A water outlet is located in the sump, and a dam is positioned in the sump upstream from the outlet. The dam, in an exemplary embodiment, is substantially perpendicular to flow path and extends from a tub sidewall to at least beyond the outer perimeter of the water outlet. The dam has a sufficient height to prevent debris heavier than water from flowing from the channel to the outlet during a non-spin portion of a wash cycle, yet is low enough so that when the spin cycle is initiated, the debris will flow over the dam to the outlet.
More particularly, and prior to operation, clothes are located in the washing machine basket and then washing machine operations are initiated by an operator. Prior to the spin cycle, the tub fills with water. Some of the water is absorbed in the clothes and some of the water is free water, i.e., not absorbed in the clothes. The free water flows down the helical path to the sump. To the extent that there is any debris in the water heavier than the water, such debris is at least partially blocked from the outlet by the dam.
Just prior to the spin cycle, the water pump is activated and water in the sump is drawn through the outlet to the pump. When the spin cycle starts, the pump continues to operate and due to the forces created during the spin cycle, debris previously blocked by the dam will flow over the top of the dam and down through the outlet to the pump. At this time, the pump has completely started-up and such debris flows into the pump without causing any plugging of the outlet and the pump.
As explained above, the sump and dam configuration prevents debris from plugging the drain hose and pump without substantially inhibiting the free flow of water through the tub outlet. Such configuration also is simple to fabricate and does not significantly increase the cost or complexity of the washing machine.